The present invention is directed to an attenuator that can be used in a variable air volume terminal unit, a terminal unit incorporating the attenuator, and clips for fastening the attenuator.
Discharge and radiated sound is of concern with variable air volume (VAV) terminal units, such as may be used in heating, ventilation, and air conditioning (HVAC) systems. In a VAV system, one or more central air supply systems are sized to meet the peak cooling (and/or heating) conditions for the building. Several terminal units are located in respective zones or offices throughout the building, each connected via ducts to the central air supply. In such a terminal unit, the volume of air urged through a diffuser over a given length of time is controlled. Some terminal units have a fan or pump driven by a motor to move the air from the central air supply through the diffuser associated with the terminal unit. VAV terminal units permit “personalizing” the temperature of a particular room or group of rooms as desired by the occupants.
While there may be several sources of objectionable sound in a HVAC system, at least every component of rotating machinery, e.g., the blower of an air handling unit, generates sound waves which propagate along the duct through the air flowing in the duct. And certain types of VAV terminal units include integral motor-driven fans. Unless attenuated to acceptable levels, the propagated sound waves may be evident to persons in the rooms served by the HVAC system. Conventional attenuators for this sound are external to the terminal unit and are either supplied and installed by the factory or are installed to the terminal unit in the field.